[aerohead]

I ran some numbers which can be attached to the Streamlining Template.
I've taken the Cd series from the fuselage data,ran the calcs starting with the Cd 0.04 L/D = 2.5 streamline body rather than the 12 % thickness fuselage of Cd 0.066.
On top of these values I've added 0.04 for the wheels,0.011 for a Korff/Morelli' cooling system,0.007 for 'Features' drag ( cut lines,door handles,wipers,mirrors,trim,etc.) based on the GM PNGV/Precept.
From this,I've 'subtracted' 0.015 for an under-car, full wheel fairing kit,as existed on the original GM Sunraycer or you'll see on the HONDA Dream-2 Solar racer.And I've subtracted an additional 0.008 for basjoos'-style full-floating front wheel skirts.
Since the Template is already broken down into ten segments,one can just pencil in the values below each 10 % segment line beginning at zero.
These values represent a conservative estimate of what we might achieve based on Template streamlining.Since the values are from full-scale wind tunnel testing with critical Reynolds number criteria applied,we should be able to use them with a high degree of confidence.
You can just choose a drag coefficient goal,find it on the Template,and build accordingly.You should be able to predict the new performance before you begin construction.
For values falling between 10 % stations you can just interpolate for a good approximation.

zero------ Cd 0.488
10 %----- Cd 0.375
20 %----- Cd 0.299
30 %----- Cd 0.240
40 %----- Cd 0.194
50 %----- Cd 0.162
60 %----- Cd 0.135
70 %----- Cd 0.125
80 %----- Cd 0.118
90 %----- Cd 0.118
100 %---- Cd 0.115

Note: Everyone will notice,that with proper ground clearance,the under-body of a vehicle projected rearward,would intersect the Template line around 80 %.You'll also notice that there is little drag reduction to be gained by going beyond 80 %.This is the region of 'phantom' tail.
For those contemplating a 100 %- length trailer,you can look at Solaraycer,1957 MG EX 181,Porsche 917 LH,or D-B C 111 III to see how they employed the Von Mises/ relev'e/ reflex-camber profile,simply bending the extra length up to clear the ground.
Final note: By taking the % Cd difference of where you are as opposed to where you want to go,half of that value will give your new HWY mpg multiplier @ 55 mph ( 88.6 Km/h ).
Happy modding!